defmodule Demo.Application do
  @moduledoc false

  use Application

  @impl true
  def start(_type, _args) do
    children = [
      Demo.Server
    ]

    opts = [strategy: :one_for_one, name: Demo.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

defmodule Demo.Server do
  use GenServer

  def start_link(arg) do
    GenServer.start_link(__MODULE__, arg, name: __MODULE__)
  end

  @impl true
  def init(_) do
    Process.flag(:trap_exit, true)
    {:ok, server_pid} = ElixirKit.start()
    log("init")

    Task.start(fn ->
      for i <- 5..1//-1 do
        log("Stopping in #{i}...")
        Process.sleep(1000)
      end

      System.stop()
    end)

    {:ok, %{server_pid: server_pid}}
  end

  @impl true
  def handle_info({:event, "log", message}, state) do
    log(message)
    {:noreply, state}
  end

  @impl true
  def handle_info({:EXIT, pid, :shutdown}, state) when pid == state.server_pid do
    {:noreply, state}
  end

  @impl true
  def terminate(_reason, _state) do
    log("Stopping...")
  end

  defp log(message) do
    IO.puts(["[server] ", message])
  end
end